1. Field of the Invention
The invention relates to an apparatus and method for unloading dry, semi-dry, or wet materials stored in flexible and rigid bulk containers.
2. Description of the Related Art
Many of the bulk materials being processed and transported in commerce have proven to be difficult to handle. Materials that are easy to handle can be stored in silos or moved in rigid containers. Materials that are difficult to handle cannot, and present difficulty. A few examples of such materials are brown sugar, cheese curd, cellulose powder, chopped fiberglass, and pigments.
The problem with these materials is that they tend to compact over time due to the effects of vibration, moisture, and storage. Because of compaction and caking, the materials cannot be properly discharged from their containers. Furthermore, some materials are naturally resistant to flow. As a result, the material may bridge over the bottom discharge opening, thus interfering with the emptying of the container. The material may also rat hole, such that it forms a hole from the discharge opening to the top of the container which stops further material from flowing.
Although some bulk containers can be emptied by lifting them high in the air, this solution is undesirable. The process requires a great deal of vertical space and lifting equipment, and can be dangerous.
Another solution is to store and transport bulk materials in small sacks that are emptied by hand. This is undesirable because of the high labor cost involved and danger to personnel in the form of back injuries. Also, the one-shipment bag is destroyed in a single use.
Other materials may incompletely compact, such that a portion of the material remains like dust or powder. The problem with these materials is that some of the material may tend to flow even before the discharge is connected to its hopper.
One solution has been to employ a flexible, side-mounted discharge bulk container as taught in U.S. Pat. No. 5,344,048. A simple unloader is disclosed in that patent as well. The unloader disclosed in the patent is capable only of inclining the side-mounted discharge bulk container to assist in the unloading process. However, some materials require more aggressive handling before they can be properly discharged from a bulk container. A simple tilting procedure may not be sufficient in every circumstance to adequately discharge bulk materials, or to unload materials with poor flowing characteristics. Also, the unloader disclosed in that patent does not address the problem of partially un-compacted materials that flow too readily. A suitable unloader has not been found in the prior art.
Therefore, it is the object of this invention to provide an unloader for bulk material containers having a side-mounted discharge that employs active mechanisms that help un-compact compacted bulk materials.
It is another object of this invention to provide an unloader capable of preventing the flow of uncompacted material before the discharge has been secured to a hopper or other device.
It is another object of this invention to provide an unloader that employs at least one of many possible mechanisms for manipulating a bulk container and mechanisms for their automatic or manual control. What is needed is an unloading apparatus that is capable of unloading extremely compacted bulk materials and bulk materials that are only partially compacted.